1. Field of the Invention
This invention relates to the locking of the trigger for a momentary switch (sometimes called "dead man" switch) in the ON position. The object of this invention is to provide a locking member which is located centrally of the trigger and adjacent to a swinging end of such trigger. This makes the device equally usable by both right and left handed operators. A further object is to provide a locking member the operating arm of which does not protrude substantially so as to be easily damaged.
2. Description of the Prior Art
In expired U.S. Pat No. 2,200,322, there is described a locking member 30 which locks the trigger 55 of a cautery handle in ON position. The locking member is not biased to non-locking position. Consequently, the operator must perform a second manual manipulation to unlock the trigger from ON position. The locking member 30 has projecting top 60 which is centrally located with respect to the trigger 55 (see FIG. 2). It is so far removed below trigger 55 that the operator cannot operate the tool 60 with the fingers of the same hand that holds the pistol-like grip and also holds the trigger 55 in ON position. The same problems appear to be present in expired U.S. Pat. No. 2,237,646, where the unlocking of the locking member 49 (swinging loop) is the force of gravity. Furthermore, the loop 49 is greatly exposed and easily damaged.
A patentability search did not uncover any patents disclosing the features of the locking member: (1) being inherently biased to unlocking position; (2) being positioned centrally of an adjacent the free end of the swinging trigger; and (3) the ratio between the length of the operating arm and the length of the locking projection on the locking member being such that a small movement of such arm creates a large movement of the locking projection.